Abstract
The frictional electrification of 6 inorganic and 13 organic medicinal crystals was examined. The crystal was slid down on flat-bottomed chute into a Faraday cylinder and the induced voltage was determined by a vacuum tube voltmeter with a very small leakage of 10-13 to 10-14 A. The prediction of the phenomenon was very difficult since the sign and the amount of charge was determined by the experimental conditions, but the following tendencies were found. 1) The charge found at the chute made of paraffin paper was larger than the one made of metal or glass. The grounding of the metal chute was not effective on avoiding frictional electrification. 2) A relatively small charge was found with water-soluble crystals and a larger one with water-insoluble crystals. 3) Acetanilide, acetophenetidine, and benzoic acid behaved quite differently, i.e. negative charges and then positive charges were found on the crystals in the chute experiment. It was evidenced that this was caused by the adhesion of crystal. 4) In the treatment of crystals with surfactant, the development of charge was reduced to about 1/100 with the combination of Aspirin-Tween 40-paraffin paper chute, but an opposite charges was observed in some cases.
